Tucana

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Tucana is a constellation in the southern hemisphere. It was introduced by the Dutch astronomer Petrus Plancius in the 16th century and first depicted in Johann Bayer's celestial atlas Uranometria in 1603. Tucana represents the toucan, a South American bird. There are no myths associated with the constellation.

The constellation Tucana occupies an area of 295 square degrees and contains three stars with known planets. It can be seen at latitudes between +25° and -90° and is best visible at 9 p.m. during the month of November.

The brightest star in the constellation is [8265] alpha Tucanae, a binary star that consists of an orange giant and a companion star that has not been directly observed. Alpha Tucanae lies approximately 199 light-years from Earth.

[8267] zeta Tucanae is an F class main sequence star smaller in mass than the Sun and yet more luminous. The star is believed to have a debris disk surrounding it. It is approximately 28 light-years distant. Its similarity to the Sun makes it an object of interest to those investigating star systems possibly containing life-baring planets. Zeta Tucanae is a member of the Ursa Major Moving Group of stars.

[8273] kappa Tucanae is a multiple star system consisting of two binary pairs of stars. The primary component is a yellow-white giant. The system lies about 67 light-years from Earth.

[8268]-[8271] beta Tucanae consists of six stars and is approximately 140 light-years distant. The two brightest stars are a blue-white dwarf and a white dwarf, both bright enough to have their own Bayer designations, [8268] beta-1 and [8271] beta-2 Tucanae. Each of them also has at least one companion star.

Tucana has several interesting deep sky objects. The Small Magellanic Cloud, a dwarf galaxy with several hundred million member stars, lies in the southern corner of the constellation. It is approximately 7,000 light-years in diameter and one of the closest neighbours to the Milky Way. The Small Magellanic Cloud belongs to the Local Group of galaxies.

47 Tucanae (NGC 104) is the second brightest globular cluster in the sky. It is 120 light-years in diameter and 16,700 light-years distant. It was discovered by the French astronomer Nicolas Louis de Lacaille in the 18th century. The cluster has a very densely populated core and contains at least 22 milisecond pulsars (pulsars with a rotational period between 1 and 10 miliseconds) and 21 blue stragglers (stars bluer and hotter than other stars in the cluster that have the same luminosity) in the central region.

The Tucana Dwarf is a spheroidal dwarf galaxy 3.2 million light-years distant. It is an isolated member of the Local Group.

NGC 346 is an open star cluster, 210,000 light-years distant. The cluster is a star forming region. It is associated with a nebula that lies in the Small Magellanic Cloud.